Well the NRCS agent came out and said I should excavate 6' or so with a 3' perimeter berm. All he had was a 6' core tool but says he "thinks" I could go deeper. I told him I'd get a posthole digger to punch some holes and he said he would bring another tool to go 10'.

A 6' dig and 3' berm gives me 9' or say at most 8' of water depth. With a uniform 8' would that end up getting to hot in this TX summer heat? I see all these posts of 12' on up to 18' deep builds. Is that just needed for ponds that depend on rain for the water supply or do the fish benefit any from water over 8'?